In a known knee protection air bag assembly, a bag expands to protect the knees of the occupant seated on the driver's seat of a vehicle, if the vehicle collides with an obstacle. Such a knee protection air bag assembly is often provided near an opening of a lower panel of a dashboard so that a bag expands from the opening, or inside a column cover so that the bag expands from an opening of the column cover.
Assume that a knee protection air bag assembly is provided so that a bag expands from an opening of a lower panel of the dashboard, as described above. In order to withstand reaction force in the expansion of the bag, the air bag assembly needs to be supported by a high-strength member such as a steering member, a center stay, and a vehicle body (particularly a dash panel). Such a high-strength member is spaced apart from the position of the air bag assembly. The air bag assembly needs to be attached to a long mount portion of the high-strength member. This may cause a problem in the layout of the mount portion, and increase the weight of the vehicle body.
On the other hand, assume that a knee protection air bag assembly is provided inside a column cover. The air bag assembly is fixed to a steering column There is no need to provide a long mount portion of the air bag assembly, which leads to reductions in the size and weight of the air bag assembly. However, if a weight of an object is supported at a portion of the steering column near a steering wheel, the vibration performance of the steering wheel would deteriorate.
To address this problem, Patent Document 1 discloses a knee protection air bag assembly, which is provided below a steering column so that a bag expands from an opening of a lower panel of the dashboard. The air bag assembly is attached to a part of the steering column apart from a steering wheel (specifically at a front end part of the steering column in the vehicle). This configuration reduces the risk of deterioration in the vibration performance of the steering wheel, and the size and weight of the air bag assembly.